A study of the impact of spatial resolution on the estimation of particle matter concentration from the aerosol optical depth retrieved from satellite observations

ABSTRACT

The relationship between satellite-derived aerosol optical depth (AOD) and ground-based near-surface particle matter concentration (PM_2.5) has been investigated with respect to spatial resolution of satellite observations. AOD data product with spatial resolution of 1 km provided by the Multi-Angle Implementation of Atmospheric Correction (MAIAC) using the Moderate Resolution Imaging Spectroradiometer (MODIS) together with PM_2.5 data measured by 946 Environmental Protection Agency (EPA) ground monitoring sites across the contiguous US have been used to study the linear relationship between AOD and PM_2.5 concentration at different spatial resolutions (1, 3, and 10 km), which is named the AOD spatial resolution effect in the manuscript, for different spatial scales (urban scale, mesoscale, and continental scale). In addition, auxiliary data sets such as meteorological conditions, aerosol properties, and surface characteristics have been analysed to study the impact on the determination of PM_2.5 concentration. The conclusions are (1) for both urban, meso-, and continental scale, the correlation between PM_2.5 and AOD increases significantly with the increase of AOD spatial resolution; (2) the correlation between AOD and near-surface PM_2.5 concentration decreases significantly as the scale of study region increases for the eastern part of the US but the opposite for the western part of the US; (3) the correlation between PM_2.5 and AOD is more stable and higher over the eastern part of the US.

Acknowledgments

We are grateful to Dr Alexei Lyapustin for providing MAIAC data and valuable discussion. We are also grateful to Dr Alexandra Chudnovsky for the important discussion that also improved the quality of the article. We also thank Dr Jan Aschmann for downloading and providing relative humidity and boundary layer height data. PM_2.5 data originate from EPA, boundary layer height and relative humidity data from ECMWF, and the surface reflectance and aerosol fine mode fraction data were provided by the MODIS aerosol science team and have been downloaded from the LAADS Web. The project is partly funded by the University and State of Bremen and the German Science Foundation (DFG) Trans Regio SFB ‘Arctic Amplification TR 172.’ This work was partly supported by the European Space Agency as part of the Aerosol_CCI project. This research is in part a contribution by IUP/UB to MARUM a DFG-Research Center/Cluster of Excellence ‘The Ocean in the Earth System’ (OC-CCP1).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the European Space Agency: [Grant Number 40101124] and Deutsche Forschungsgemeinschaft: [Grant Number 40101200, EXC 309].